mirror of https://gitee.com/openkylin/linux.git
803 lines
20 KiB
C
803 lines
20 KiB
C
/*
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* arch/arm/common/bL_switcher.c -- big.LITTLE cluster switcher core driver
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*
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* Created by: Nicolas Pitre, March 2012
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* Copyright: (C) 2012-2013 Linaro Limited
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/atomic.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/interrupt.h>
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#include <linux/cpu_pm.h>
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#include <linux/cpu.h>
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#include <linux/cpumask.h>
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#include <linux/kthread.h>
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#include <linux/wait.h>
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#include <linux/time.h>
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#include <linux/clockchips.h>
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#include <linux/hrtimer.h>
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#include <linux/tick.h>
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#include <linux/notifier.h>
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#include <linux/mm.h>
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#include <linux/mutex.h>
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#include <linux/smp.h>
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#include <linux/spinlock.h>
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#include <linux/string.h>
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#include <linux/sysfs.h>
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#include <linux/irqchip/arm-gic.h>
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#include <linux/moduleparam.h>
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#include <asm/smp_plat.h>
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#include <asm/cputype.h>
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#include <asm/suspend.h>
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#include <asm/mcpm.h>
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#include <asm/bL_switcher.h>
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#define CREATE_TRACE_POINTS
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#include <trace/events/power_cpu_migrate.h>
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/*
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* Use our own MPIDR accessors as the generic ones in asm/cputype.h have
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* __attribute_const__ and we don't want the compiler to assume any
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* constness here as the value _does_ change along some code paths.
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*/
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static int read_mpidr(void)
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{
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unsigned int id;
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asm volatile ("mrc p15, 0, %0, c0, c0, 5" : "=r" (id));
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return id & MPIDR_HWID_BITMASK;
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}
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/*
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* bL switcher core code.
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*/
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static void bL_do_switch(void *_arg)
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{
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unsigned ib_mpidr, ib_cpu, ib_cluster;
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long volatile handshake, **handshake_ptr = _arg;
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pr_debug("%s\n", __func__);
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ib_mpidr = cpu_logical_map(smp_processor_id());
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ib_cpu = MPIDR_AFFINITY_LEVEL(ib_mpidr, 0);
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ib_cluster = MPIDR_AFFINITY_LEVEL(ib_mpidr, 1);
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/* Advertise our handshake location */
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if (handshake_ptr) {
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handshake = 0;
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*handshake_ptr = &handshake;
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} else
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handshake = -1;
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/*
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* Our state has been saved at this point. Let's release our
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* inbound CPU.
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*/
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mcpm_set_entry_vector(ib_cpu, ib_cluster, cpu_resume);
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sev();
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/*
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* From this point, we must assume that our counterpart CPU might
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* have taken over in its parallel world already, as if execution
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* just returned from cpu_suspend(). It is therefore important to
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* be very careful not to make any change the other guy is not
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* expecting. This is why we need stack isolation.
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*
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* Fancy under cover tasks could be performed here. For now
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* we have none.
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*/
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/*
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* Let's wait until our inbound is alive.
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*/
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while (!handshake) {
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wfe();
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smp_mb();
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}
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/* Let's put ourself down. */
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mcpm_cpu_power_down();
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/* should never get here */
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BUG();
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}
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/*
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* Stack isolation. To ensure 'current' remains valid, we just use another
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* piece of our thread's stack space which should be fairly lightly used.
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* The selected area starts just above the thread_info structure located
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* at the very bottom of the stack, aligned to a cache line, and indexed
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* with the cluster number.
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*/
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#define STACK_SIZE 512
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extern void call_with_stack(void (*fn)(void *), void *arg, void *sp);
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static int bL_switchpoint(unsigned long _arg)
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{
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unsigned int mpidr = read_mpidr();
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unsigned int clusterid = MPIDR_AFFINITY_LEVEL(mpidr, 1);
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void *stack = current_thread_info() + 1;
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stack = PTR_ALIGN(stack, L1_CACHE_BYTES);
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stack += clusterid * STACK_SIZE + STACK_SIZE;
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call_with_stack(bL_do_switch, (void *)_arg, stack);
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BUG();
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}
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/*
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* Generic switcher interface
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*/
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static unsigned int bL_gic_id[MAX_CPUS_PER_CLUSTER][MAX_NR_CLUSTERS];
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static int bL_switcher_cpu_pairing[NR_CPUS];
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/*
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* bL_switch_to - Switch to a specific cluster for the current CPU
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* @new_cluster_id: the ID of the cluster to switch to.
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*
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* This function must be called on the CPU to be switched.
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* Returns 0 on success, else a negative status code.
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*/
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static int bL_switch_to(unsigned int new_cluster_id)
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{
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unsigned int mpidr, this_cpu, that_cpu;
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unsigned int ob_mpidr, ob_cpu, ob_cluster, ib_mpidr, ib_cpu, ib_cluster;
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struct completion inbound_alive;
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long volatile *handshake_ptr;
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int ipi_nr, ret;
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this_cpu = smp_processor_id();
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ob_mpidr = read_mpidr();
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ob_cpu = MPIDR_AFFINITY_LEVEL(ob_mpidr, 0);
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ob_cluster = MPIDR_AFFINITY_LEVEL(ob_mpidr, 1);
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BUG_ON(cpu_logical_map(this_cpu) != ob_mpidr);
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if (new_cluster_id == ob_cluster)
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return 0;
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that_cpu = bL_switcher_cpu_pairing[this_cpu];
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ib_mpidr = cpu_logical_map(that_cpu);
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ib_cpu = MPIDR_AFFINITY_LEVEL(ib_mpidr, 0);
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ib_cluster = MPIDR_AFFINITY_LEVEL(ib_mpidr, 1);
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pr_debug("before switch: CPU %d MPIDR %#x -> %#x\n",
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this_cpu, ob_mpidr, ib_mpidr);
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this_cpu = smp_processor_id();
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/* Close the gate for our entry vectors */
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mcpm_set_entry_vector(ob_cpu, ob_cluster, NULL);
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mcpm_set_entry_vector(ib_cpu, ib_cluster, NULL);
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/* Install our "inbound alive" notifier. */
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init_completion(&inbound_alive);
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ipi_nr = register_ipi_completion(&inbound_alive, this_cpu);
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ipi_nr |= ((1 << 16) << bL_gic_id[ob_cpu][ob_cluster]);
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mcpm_set_early_poke(ib_cpu, ib_cluster, gic_get_sgir_physaddr(), ipi_nr);
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/*
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* Let's wake up the inbound CPU now in case it requires some delay
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* to come online, but leave it gated in our entry vector code.
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*/
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ret = mcpm_cpu_power_up(ib_cpu, ib_cluster);
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if (ret) {
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pr_err("%s: mcpm_cpu_power_up() returned %d\n", __func__, ret);
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return ret;
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}
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/*
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* Raise a SGI on the inbound CPU to make sure it doesn't stall
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* in a possible WFI, such as in bL_power_down().
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*/
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gic_send_sgi(bL_gic_id[ib_cpu][ib_cluster], 0);
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/*
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* Wait for the inbound to come up. This allows for other
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* tasks to be scheduled in the mean time.
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*/
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wait_for_completion(&inbound_alive);
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mcpm_set_early_poke(ib_cpu, ib_cluster, 0, 0);
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/*
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* From this point we are entering the switch critical zone
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* and can't take any interrupts anymore.
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*/
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local_irq_disable();
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local_fiq_disable();
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trace_cpu_migrate_begin(ktime_get_real_ns(), ob_mpidr);
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/* redirect GIC's SGIs to our counterpart */
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gic_migrate_target(bL_gic_id[ib_cpu][ib_cluster]);
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tick_suspend_local();
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ret = cpu_pm_enter();
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/* we can not tolerate errors at this point */
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if (ret)
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panic("%s: cpu_pm_enter() returned %d\n", __func__, ret);
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/* Swap the physical CPUs in the logical map for this logical CPU. */
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cpu_logical_map(this_cpu) = ib_mpidr;
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cpu_logical_map(that_cpu) = ob_mpidr;
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/* Let's do the actual CPU switch. */
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ret = cpu_suspend((unsigned long)&handshake_ptr, bL_switchpoint);
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if (ret > 0)
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panic("%s: cpu_suspend() returned %d\n", __func__, ret);
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/* We are executing on the inbound CPU at this point */
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mpidr = read_mpidr();
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pr_debug("after switch: CPU %d MPIDR %#x\n", this_cpu, mpidr);
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BUG_ON(mpidr != ib_mpidr);
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mcpm_cpu_powered_up();
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ret = cpu_pm_exit();
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tick_resume_local();
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trace_cpu_migrate_finish(ktime_get_real_ns(), ib_mpidr);
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local_fiq_enable();
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local_irq_enable();
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*handshake_ptr = 1;
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dsb_sev();
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if (ret)
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pr_err("%s exiting with error %d\n", __func__, ret);
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return ret;
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}
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struct bL_thread {
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spinlock_t lock;
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struct task_struct *task;
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wait_queue_head_t wq;
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int wanted_cluster;
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struct completion started;
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bL_switch_completion_handler completer;
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void *completer_cookie;
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};
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static struct bL_thread bL_threads[NR_CPUS];
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static int bL_switcher_thread(void *arg)
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{
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struct bL_thread *t = arg;
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struct sched_param param = { .sched_priority = 1 };
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int cluster;
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bL_switch_completion_handler completer;
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void *completer_cookie;
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sched_setscheduler_nocheck(current, SCHED_FIFO, ¶m);
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complete(&t->started);
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do {
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if (signal_pending(current))
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flush_signals(current);
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wait_event_interruptible(t->wq,
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t->wanted_cluster != -1 ||
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kthread_should_stop());
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spin_lock(&t->lock);
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cluster = t->wanted_cluster;
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completer = t->completer;
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completer_cookie = t->completer_cookie;
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t->wanted_cluster = -1;
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t->completer = NULL;
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spin_unlock(&t->lock);
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if (cluster != -1) {
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bL_switch_to(cluster);
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if (completer)
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completer(completer_cookie);
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}
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} while (!kthread_should_stop());
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return 0;
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}
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static struct task_struct *bL_switcher_thread_create(int cpu, void *arg)
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{
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struct task_struct *task;
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task = kthread_create_on_node(bL_switcher_thread, arg,
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cpu_to_node(cpu), "kswitcher_%d", cpu);
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if (!IS_ERR(task)) {
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kthread_bind(task, cpu);
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wake_up_process(task);
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} else
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pr_err("%s failed for CPU %d\n", __func__, cpu);
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return task;
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}
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/*
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* bL_switch_request_cb - Switch to a specific cluster for the given CPU,
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* with completion notification via a callback
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*
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* @cpu: the CPU to switch
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* @new_cluster_id: the ID of the cluster to switch to.
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* @completer: switch completion callback. if non-NULL,
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* @completer(@completer_cookie) will be called on completion of
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* the switch, in non-atomic context.
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* @completer_cookie: opaque context argument for @completer.
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*
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* This function causes a cluster switch on the given CPU by waking up
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* the appropriate switcher thread. This function may or may not return
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* before the switch has occurred.
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*
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* If a @completer callback function is supplied, it will be called when
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* the switch is complete. This can be used to determine asynchronously
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* when the switch is complete, regardless of when bL_switch_request()
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* returns. When @completer is supplied, no new switch request is permitted
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* for the affected CPU until after the switch is complete, and @completer
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* has returned.
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*/
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int bL_switch_request_cb(unsigned int cpu, unsigned int new_cluster_id,
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bL_switch_completion_handler completer,
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void *completer_cookie)
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{
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struct bL_thread *t;
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if (cpu >= ARRAY_SIZE(bL_threads)) {
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pr_err("%s: cpu %d out of bounds\n", __func__, cpu);
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return -EINVAL;
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}
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t = &bL_threads[cpu];
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if (IS_ERR(t->task))
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return PTR_ERR(t->task);
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if (!t->task)
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return -ESRCH;
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spin_lock(&t->lock);
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if (t->completer) {
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spin_unlock(&t->lock);
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return -EBUSY;
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}
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t->completer = completer;
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t->completer_cookie = completer_cookie;
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t->wanted_cluster = new_cluster_id;
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spin_unlock(&t->lock);
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wake_up(&t->wq);
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return 0;
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}
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EXPORT_SYMBOL_GPL(bL_switch_request_cb);
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/*
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* Activation and configuration code.
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*/
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static DEFINE_MUTEX(bL_switcher_activation_lock);
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static BLOCKING_NOTIFIER_HEAD(bL_activation_notifier);
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static unsigned int bL_switcher_active;
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static unsigned int bL_switcher_cpu_original_cluster[NR_CPUS];
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static cpumask_t bL_switcher_removed_logical_cpus;
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int bL_switcher_register_notifier(struct notifier_block *nb)
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{
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return blocking_notifier_chain_register(&bL_activation_notifier, nb);
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}
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EXPORT_SYMBOL_GPL(bL_switcher_register_notifier);
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int bL_switcher_unregister_notifier(struct notifier_block *nb)
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{
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return blocking_notifier_chain_unregister(&bL_activation_notifier, nb);
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}
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EXPORT_SYMBOL_GPL(bL_switcher_unregister_notifier);
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static int bL_activation_notify(unsigned long val)
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{
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int ret;
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ret = blocking_notifier_call_chain(&bL_activation_notifier, val, NULL);
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if (ret & NOTIFY_STOP_MASK)
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pr_err("%s: notifier chain failed with status 0x%x\n",
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__func__, ret);
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return notifier_to_errno(ret);
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}
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static void bL_switcher_restore_cpus(void)
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{
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int i;
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for_each_cpu(i, &bL_switcher_removed_logical_cpus) {
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struct device *cpu_dev = get_cpu_device(i);
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int ret = device_online(cpu_dev);
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if (ret)
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dev_err(cpu_dev, "switcher: unable to restore CPU\n");
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}
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}
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static int bL_switcher_halve_cpus(void)
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{
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int i, j, cluster_0, gic_id, ret;
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unsigned int cpu, cluster, mask;
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cpumask_t available_cpus;
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/* First pass to validate what we have */
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mask = 0;
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for_each_online_cpu(i) {
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cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 0);
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cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1);
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if (cluster >= 2) {
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pr_err("%s: only dual cluster systems are supported\n", __func__);
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return -EINVAL;
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}
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if (WARN_ON(cpu >= MAX_CPUS_PER_CLUSTER))
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return -EINVAL;
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mask |= (1 << cluster);
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}
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if (mask != 3) {
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pr_err("%s: no CPU pairing possible\n", __func__);
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return -EINVAL;
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}
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/*
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* Now let's do the pairing. We match each CPU with another CPU
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* from a different cluster. To get a uniform scheduling behavior
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* without fiddling with CPU topology and compute capacity data,
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* we'll use logical CPUs initially belonging to the same cluster.
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*/
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memset(bL_switcher_cpu_pairing, -1, sizeof(bL_switcher_cpu_pairing));
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cpumask_copy(&available_cpus, cpu_online_mask);
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cluster_0 = -1;
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for_each_cpu(i, &available_cpus) {
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int match = -1;
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cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1);
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if (cluster_0 == -1)
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cluster_0 = cluster;
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if (cluster != cluster_0)
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continue;
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cpumask_clear_cpu(i, &available_cpus);
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for_each_cpu(j, &available_cpus) {
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cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(j), 1);
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/*
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* Let's remember the last match to create "odd"
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* pairings on purpose in order for other code not
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* to assume any relation between physical and
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* logical CPU numbers.
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*/
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if (cluster != cluster_0)
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match = j;
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}
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if (match != -1) {
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bL_switcher_cpu_pairing[i] = match;
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cpumask_clear_cpu(match, &available_cpus);
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pr_info("CPU%d paired with CPU%d\n", i, match);
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}
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}
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/*
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* Now we disable the unwanted CPUs i.e. everything that has no
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* pairing information (that includes the pairing counterparts).
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*/
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cpumask_clear(&bL_switcher_removed_logical_cpus);
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for_each_online_cpu(i) {
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cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 0);
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cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1);
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/* Let's take note of the GIC ID for this CPU */
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gic_id = gic_get_cpu_id(i);
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if (gic_id < 0) {
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pr_err("%s: bad GIC ID for CPU %d\n", __func__, i);
|
|
bL_switcher_restore_cpus();
|
|
return -EINVAL;
|
|
}
|
|
bL_gic_id[cpu][cluster] = gic_id;
|
|
pr_info("GIC ID for CPU %u cluster %u is %u\n",
|
|
cpu, cluster, gic_id);
|
|
|
|
if (bL_switcher_cpu_pairing[i] != -1) {
|
|
bL_switcher_cpu_original_cluster[i] = cluster;
|
|
continue;
|
|
}
|
|
|
|
ret = device_offline(get_cpu_device(i));
|
|
if (ret) {
|
|
bL_switcher_restore_cpus();
|
|
return ret;
|
|
}
|
|
cpumask_set_cpu(i, &bL_switcher_removed_logical_cpus);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* Determine the logical CPU a given physical CPU is grouped on. */
|
|
int bL_switcher_get_logical_index(u32 mpidr)
|
|
{
|
|
int cpu;
|
|
|
|
if (!bL_switcher_active)
|
|
return -EUNATCH;
|
|
|
|
mpidr &= MPIDR_HWID_BITMASK;
|
|
for_each_online_cpu(cpu) {
|
|
int pairing = bL_switcher_cpu_pairing[cpu];
|
|
if (pairing == -1)
|
|
continue;
|
|
if ((mpidr == cpu_logical_map(cpu)) ||
|
|
(mpidr == cpu_logical_map(pairing)))
|
|
return cpu;
|
|
}
|
|
return -EINVAL;
|
|
}
|
|
|
|
static void bL_switcher_trace_trigger_cpu(void *__always_unused info)
|
|
{
|
|
trace_cpu_migrate_current(ktime_get_real_ns(), read_mpidr());
|
|
}
|
|
|
|
int bL_switcher_trace_trigger(void)
|
|
{
|
|
int ret;
|
|
|
|
preempt_disable();
|
|
|
|
bL_switcher_trace_trigger_cpu(NULL);
|
|
ret = smp_call_function(bL_switcher_trace_trigger_cpu, NULL, true);
|
|
|
|
preempt_enable();
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(bL_switcher_trace_trigger);
|
|
|
|
static int bL_switcher_enable(void)
|
|
{
|
|
int cpu, ret;
|
|
|
|
mutex_lock(&bL_switcher_activation_lock);
|
|
lock_device_hotplug();
|
|
if (bL_switcher_active) {
|
|
unlock_device_hotplug();
|
|
mutex_unlock(&bL_switcher_activation_lock);
|
|
return 0;
|
|
}
|
|
|
|
pr_info("big.LITTLE switcher initializing\n");
|
|
|
|
ret = bL_activation_notify(BL_NOTIFY_PRE_ENABLE);
|
|
if (ret)
|
|
goto error;
|
|
|
|
ret = bL_switcher_halve_cpus();
|
|
if (ret)
|
|
goto error;
|
|
|
|
bL_switcher_trace_trigger();
|
|
|
|
for_each_online_cpu(cpu) {
|
|
struct bL_thread *t = &bL_threads[cpu];
|
|
spin_lock_init(&t->lock);
|
|
init_waitqueue_head(&t->wq);
|
|
init_completion(&t->started);
|
|
t->wanted_cluster = -1;
|
|
t->task = bL_switcher_thread_create(cpu, t);
|
|
}
|
|
|
|
bL_switcher_active = 1;
|
|
bL_activation_notify(BL_NOTIFY_POST_ENABLE);
|
|
pr_info("big.LITTLE switcher initialized\n");
|
|
goto out;
|
|
|
|
error:
|
|
pr_warn("big.LITTLE switcher initialization failed\n");
|
|
bL_activation_notify(BL_NOTIFY_POST_DISABLE);
|
|
|
|
out:
|
|
unlock_device_hotplug();
|
|
mutex_unlock(&bL_switcher_activation_lock);
|
|
return ret;
|
|
}
|
|
|
|
#ifdef CONFIG_SYSFS
|
|
|
|
static void bL_switcher_disable(void)
|
|
{
|
|
unsigned int cpu, cluster;
|
|
struct bL_thread *t;
|
|
struct task_struct *task;
|
|
|
|
mutex_lock(&bL_switcher_activation_lock);
|
|
lock_device_hotplug();
|
|
|
|
if (!bL_switcher_active)
|
|
goto out;
|
|
|
|
if (bL_activation_notify(BL_NOTIFY_PRE_DISABLE) != 0) {
|
|
bL_activation_notify(BL_NOTIFY_POST_ENABLE);
|
|
goto out;
|
|
}
|
|
|
|
bL_switcher_active = 0;
|
|
|
|
/*
|
|
* To deactivate the switcher, we must shut down the switcher
|
|
* threads to prevent any other requests from being accepted.
|
|
* Then, if the final cluster for given logical CPU is not the
|
|
* same as the original one, we'll recreate a switcher thread
|
|
* just for the purpose of switching the CPU back without any
|
|
* possibility for interference from external requests.
|
|
*/
|
|
for_each_online_cpu(cpu) {
|
|
t = &bL_threads[cpu];
|
|
task = t->task;
|
|
t->task = NULL;
|
|
if (!task || IS_ERR(task))
|
|
continue;
|
|
kthread_stop(task);
|
|
/* no more switch may happen on this CPU at this point */
|
|
cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1);
|
|
if (cluster == bL_switcher_cpu_original_cluster[cpu])
|
|
continue;
|
|
init_completion(&t->started);
|
|
t->wanted_cluster = bL_switcher_cpu_original_cluster[cpu];
|
|
task = bL_switcher_thread_create(cpu, t);
|
|
if (!IS_ERR(task)) {
|
|
wait_for_completion(&t->started);
|
|
kthread_stop(task);
|
|
cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1);
|
|
if (cluster == bL_switcher_cpu_original_cluster[cpu])
|
|
continue;
|
|
}
|
|
/* If execution gets here, we're in trouble. */
|
|
pr_crit("%s: unable to restore original cluster for CPU %d\n",
|
|
__func__, cpu);
|
|
pr_crit("%s: CPU %d can't be restored\n",
|
|
__func__, bL_switcher_cpu_pairing[cpu]);
|
|
cpumask_clear_cpu(bL_switcher_cpu_pairing[cpu],
|
|
&bL_switcher_removed_logical_cpus);
|
|
}
|
|
|
|
bL_switcher_restore_cpus();
|
|
bL_switcher_trace_trigger();
|
|
|
|
bL_activation_notify(BL_NOTIFY_POST_DISABLE);
|
|
|
|
out:
|
|
unlock_device_hotplug();
|
|
mutex_unlock(&bL_switcher_activation_lock);
|
|
}
|
|
|
|
static ssize_t bL_switcher_active_show(struct kobject *kobj,
|
|
struct kobj_attribute *attr, char *buf)
|
|
{
|
|
return sprintf(buf, "%u\n", bL_switcher_active);
|
|
}
|
|
|
|
static ssize_t bL_switcher_active_store(struct kobject *kobj,
|
|
struct kobj_attribute *attr, const char *buf, size_t count)
|
|
{
|
|
int ret;
|
|
|
|
switch (buf[0]) {
|
|
case '0':
|
|
bL_switcher_disable();
|
|
ret = 0;
|
|
break;
|
|
case '1':
|
|
ret = bL_switcher_enable();
|
|
break;
|
|
default:
|
|
ret = -EINVAL;
|
|
}
|
|
|
|
return (ret >= 0) ? count : ret;
|
|
}
|
|
|
|
static ssize_t bL_switcher_trace_trigger_store(struct kobject *kobj,
|
|
struct kobj_attribute *attr, const char *buf, size_t count)
|
|
{
|
|
int ret = bL_switcher_trace_trigger();
|
|
|
|
return ret ? ret : count;
|
|
}
|
|
|
|
static struct kobj_attribute bL_switcher_active_attr =
|
|
__ATTR(active, 0644, bL_switcher_active_show, bL_switcher_active_store);
|
|
|
|
static struct kobj_attribute bL_switcher_trace_trigger_attr =
|
|
__ATTR(trace_trigger, 0200, NULL, bL_switcher_trace_trigger_store);
|
|
|
|
static struct attribute *bL_switcher_attrs[] = {
|
|
&bL_switcher_active_attr.attr,
|
|
&bL_switcher_trace_trigger_attr.attr,
|
|
NULL,
|
|
};
|
|
|
|
static struct attribute_group bL_switcher_attr_group = {
|
|
.attrs = bL_switcher_attrs,
|
|
};
|
|
|
|
static struct kobject *bL_switcher_kobj;
|
|
|
|
static int __init bL_switcher_sysfs_init(void)
|
|
{
|
|
int ret;
|
|
|
|
bL_switcher_kobj = kobject_create_and_add("bL_switcher", kernel_kobj);
|
|
if (!bL_switcher_kobj)
|
|
return -ENOMEM;
|
|
ret = sysfs_create_group(bL_switcher_kobj, &bL_switcher_attr_group);
|
|
if (ret)
|
|
kobject_put(bL_switcher_kobj);
|
|
return ret;
|
|
}
|
|
|
|
#endif /* CONFIG_SYSFS */
|
|
|
|
bool bL_switcher_get_enabled(void)
|
|
{
|
|
mutex_lock(&bL_switcher_activation_lock);
|
|
|
|
return bL_switcher_active;
|
|
}
|
|
EXPORT_SYMBOL_GPL(bL_switcher_get_enabled);
|
|
|
|
void bL_switcher_put_enabled(void)
|
|
{
|
|
mutex_unlock(&bL_switcher_activation_lock);
|
|
}
|
|
EXPORT_SYMBOL_GPL(bL_switcher_put_enabled);
|
|
|
|
/*
|
|
* Veto any CPU hotplug operation on those CPUs we've removed
|
|
* while the switcher is active.
|
|
* We're just not ready to deal with that given the trickery involved.
|
|
*/
|
|
static int bL_switcher_hotplug_callback(struct notifier_block *nfb,
|
|
unsigned long action, void *hcpu)
|
|
{
|
|
if (bL_switcher_active) {
|
|
int pairing = bL_switcher_cpu_pairing[(unsigned long)hcpu];
|
|
switch (action & 0xf) {
|
|
case CPU_UP_PREPARE:
|
|
case CPU_DOWN_PREPARE:
|
|
if (pairing == -1)
|
|
return NOTIFY_BAD;
|
|
}
|
|
}
|
|
return NOTIFY_DONE;
|
|
}
|
|
|
|
static bool no_bL_switcher;
|
|
core_param(no_bL_switcher, no_bL_switcher, bool, 0644);
|
|
|
|
static int __init bL_switcher_init(void)
|
|
{
|
|
int ret;
|
|
|
|
if (!mcpm_is_available())
|
|
return -ENODEV;
|
|
|
|
cpu_notifier(bL_switcher_hotplug_callback, 0);
|
|
|
|
if (!no_bL_switcher) {
|
|
ret = bL_switcher_enable();
|
|
if (ret)
|
|
return ret;
|
|
}
|
|
|
|
#ifdef CONFIG_SYSFS
|
|
ret = bL_switcher_sysfs_init();
|
|
if (ret)
|
|
pr_err("%s: unable to create sysfs entry\n", __func__);
|
|
#endif
|
|
|
|
return 0;
|
|
}
|
|
|
|
late_initcall(bL_switcher_init);
|